Do waterbirds determine the distribution of aquatic plants on the Kuril Archipelago (North-Western Pacific)?

Aquatic plant ranges are supposed to be considerably shaped by long-distance dispersal with waterbirds. However, frequency and spatial patterns of such dispersal are difficult to quantify directly. Constant plant-bird associations, being an important indirect estimate of dispersal intensity, are poorly studied. Thus, we aimed to test for concordance between taxonomic diversity of aquatic plants and waterbirds, performing their simultaneous survey on certain almost uninhabited Northern West Pacific islands (northern part of East Asian-Australasian flyway). In July–August 2024, we investigated 10 survey areas on three northern Kuril islands (Paramushir, Shumshu, and Kharimkotan), differing in size and landscape diversity. We obtained new data on diversity of aquatic plants and waterbirds for separate islands and for the Kuril Archipelago in general. Aquatic flora of the smallest and the most oceanic Kharimkotan Island was unexpectedly rich. We observed the highest aquatic plant and waterbird diversity in the same three survey areas on Paramushir and Shumshu islands. This is in line with the hypothesized concordance of plant and bird diversity in aquatic ecosystems. The identified areas of high taxonomic richness of both aquatic plants and waterbirds on the Northern Kurils should be of the first priority when planning conservation activities in the region.